I think these segment protectors were home made. You can get the ones you need either from Airstream dealers or.....Inland Andy.
I did some restorative work to a '76 that had the segment protectors badly warped from excessive heat (don't ask how) and the owner got new ones that matched perfectly from Andy. Try both sources and see how you make out.
Lew Farber...RVIA Certified Master Tech...ABYC Certified Master Marine Electrician SOLAR TECH ENERGY SYSTEMS, INC. AM SOLAR ...MAGNUM…VICTRON ENERGY...LITHIUM & LIFELINE BATTERIES…MARINE REFRIGERATION